Hand held sanding blocks and power hand held and stationary sanders are well known in the art of abrading tools. One type of hand held sanding block is used with an elongated strip of sand paper and is provided with retaining means, such as spikes or clamps, at each end to cage opposed ends of such elongated strip. Another type of the hand held sanding block is used with a continuous sanding belt.
The disadvantage of the presently used sanding blocks is that the installation of the elongated sanding strip requires a considerable manual effort in order to achieve proper tension therein. Such manual effort may cause an undesirable strain and fatigue during frequent changes of the elongated sanding strips.
When the hand held sanding block is used with a continuous sanding belt, a tension mechanism must be employed in order to achieve proper tension in such continuous sanding belt. U.S. Pat. No. 6,196,909 to Cadrobbi discloses a separate wedge inserted between the belt and the block and slideable along the block until proper tension is achieved. The disadvantage of such prior art is that the wedge may be easily misplaced during storage or shift during use.
U.S. Pat. No. 6,663,479 to Sendelbeck discloses another type of tension mechanism for a hand held sanding block wherein a two portion swivel block is employed and wherein such portions are rotatable about one another in one direction to apply tension and in the opposite direction to release the tension. The disadvantage of such tension mechanism is that when the tension is achieved, one portion extends beyond the edges of another portion resulting in increased size of the sanding block.
The powered sanders are primarily used with continuous sanding belts and employ a driving element such as a pulley or a wheel connected to a prime mover such as an electric motor and a driven element connected to the driving element with a rigid linkage or a frame. The driving and driven elements are directly or indirectly engaged with the sanding belt and enable rotary motion thereof upon activation of the prime mover.
Various belt tensioning devices disclosed in U.S. Pat. No. 6,537,142 to Liou; U.S. Pat. No. 6,475,075 to Wuensch; U.S. Pat. No. 6,299,512 to Costa et al; U.S. Pat. No. 6,174,226 to Frech et al; and U.S. Pat. No. 5,183,441 to Urda utilize complex linkages and levers in order to apply and release tension in the continuous sanding belt.
Therefore, there is a need for an improved simple and economical apparatus for use with one of a hand held sanding block and a power sander for applying and releasing tension in one of the elongated sanding strip and continuous sanding belt.